hi im new in this forum, and i wanted to know how much boost a stock 325m20 engine with a thicker headgasket can take?? or would it be any difference if i used a turbo or a S.charger..

FuryriderX

04-27-2007 07:18 PM

first of all welcome, hope you enjoy your stay.

afaik boost is boost, i dont think theres a difference between turbo and s/c as far as engine longevity goes.

some people have boosted to 12 psi+ with 100% stock internals. i wouldnt consider this reliable, though. 7-8 psi is probably more reasonable, it wouldnt last forever, but no aftermarket f/i system will.

thinair

04-28-2007 09:52 AM

Boost is not boost. If a motor can withstand like 15psi of turbo boost it doesn't mean it's going to hold 15psi of supercharger boost. The way the power comes on is very different.

90E30i

04-28-2007 04:22 PM

Quote:

Boost is not boost. If a motor can withstand like 15psi of turbo boost it doesn't mean it's going to hold 15psi of supercharger boost. The way the power comes on is very different.

X 2

You can run 15-18 psi on a stock m20 without any issues but as long as its perfectly tunned.

E30-dk

04-28-2007 04:50 PM

thx.

hee hee well guess im going to take at trip down the shop and get some forged pistons and rods and a megasquirt. but what do u guys recomend Turbo or an S.charger what will last the longest? im counting on running about 18-20 psi

AceOfSpades

04-28-2007 07:42 PM

supercharger(i dunno shit about FI) and make sure it whines!!!!!!!!!!!!!!!!!!!

welcome to max*wave*

90E30i

04-28-2007 10:31 PM

Quote:

hee hee well guess im going to take at trip down the shop and get some forged pistons and rods and a megasquirt. but what do u guys recomend Turbo or an S.charger what will last the longest? im counting on running about 18-20 psi

20 psi on a turbo and 20 psi on a supercharger are two different things...the amount of power that you would make on 10 psi of turbo boost, you would make the same power running about 7-8 psi of supercharger boost.

personnaly I'd go with turbo, basically because you have alot more room for improvment. and its more effeciant.

Here is my setup BTW...ETA bottom end "I" head...planning on running about 15 psi for daily driving and about 20-25 for the track.

90E30i

04-28-2007 10:33 PM

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FuryriderX

04-29-2007 12:49 AM

Quote:

Originally Posted by 90E30i

20 psi on a turbo and 20 psi on a supercharger are two different things...the amount of power that you would make on 10 psi of turbo boost, you would make the same power running about 7-8 psi of supercharger boost.

this is cool, i did not know. how exactly are the forces different?

90E30i

04-29-2007 02:30 AM

Quote:

this is cool, i did not know. how exactly are the forces different?

I think the biggest reason you'd get more power with the supercharger is because there is no lag. other reason IMO is that most people don't know how to chose the right size turbo for their specific application and power goals, in most cases they get a turbo that's too small which causes it to die down in the higher rpms.

E30-dk

04-29-2007 04:20 AM

:d

well ive got a rotrex s.charger and a garret turbo in a 72 trim so i could go both ways, do you guys know how much hp/torque one would need to make should we under 12sec times on the dragstrip:D

90E30i

04-29-2007 01:12 PM

Quote:

well ive got a rotrex s.charger and a garret turbo in a 72 trim so i could go both ways, do you guys know how much hp/torque one would need to make should we under 12sec times on the dragstrip

It takes alot more then just power to be able to run a good time down the track. It takes the right suspension/ tires, driver skill and the weight of the car makes a huge difference. In a loaded 2 door E30 with street tires, you would need about 250-280 whp in order to run a 12 sec time down the track provided that the car is setup just right.

E30-dk

04-29-2007 02:25 PM

:d

well as for skillz ive got them down have been driving rally for the past year and often been taking my own car to "illegal" gatherings at night( in my old car) an kept a pretty good winningstreek, as for suspension ive got a koni fully adjustable and my beamer is a 2 door so it takes a bit of the weight isue..
thx for all the nice tips and facts